As new demands are placed on the electric power system, more transmission lines are built and/or upgraded in existing right-of-ways, and fewer maintenance outages are accommodated, maintenance personnel are encountering new challenges in their work. One of these challenges pertains to Ground Potential Rise (GPR).
During the repair of a transmission line, personal protective ground cables are installed to safely transfer electric current away from workers in the area into the earth through a work site ground system. This electric current may be generated by various means, such as, electromagnetic induction from a nearby current carrying line. Unfortunately, the earth is not an ideal conductor and as more current passes into the ground, the ground potential of the earth at and around the work site ground increases. As this ground potential changes, workers may be exposed to dangerous voltages.
Currently the only method of safely minimizing GPR is the use of a plurality of grounding cables carrying current into the earth at multiple points. Unfortunately, this does not solve the problem of GPR, but only lowers peak voltages at the cost of spreading the voltage across a larger area. This not only fails to eliminate GPR or notify users of a GPR issue, but may spread GPR to an area considered away from the worksite.
Therefore, there exists a need to safely detect the presence of GPR. Once GPR is detected, specialized equipment (e.g. highly insulated boots, gloves, etc. . . . ) may be used by workers to perform their work safely.